DC Current Electrodeposition of High Mo Content Ni-Mo Alloy Coatings from Alkaline Solutions

Abstract

The binary Ni-Mo alloy coatings of high Mo content were obtained on a steel substrate by dc current electrodeposition from alkaline solutions of pH 7.5-9.0. The pyrophosphate baths contained nickel chloride as a source of nickel ions, and dihydrate sodium molybdate supplied molybdenum. The constant current electrodpeposition at the deposition current denisty ofjd= 30-240 mA cm-2was performed at 60°C. The physical and chemical properties of the obtained electrocoatings were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray fluorescence (XRF) methods. All obtained Ni-Mo alloys reveal the amorphous structure, and their chemical composition strongly depends on the operating parameters of electrodeposition. The maximal content of Mo was found to be 45 at.%. The complicated mechanism of the induced co-deposition of the Ni-Mo alloy, has been discussed.